The present invention is in the field of biochemistry. More specifically, the invention involves fructosamine oxidase enzyme inhibitors. Methods of treatment, pharmaceutical compositions, dosage forms, uses of fructosamine oxidase enzyme inhibitors in medicine or for manufacturing pharmaceutical compositions, treatment regimes, and related combinations, methods and products are disclosed herein.
Diabetes mellitus is a common disorder affecting nearly 16 million Americans. See, for example, Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Diabetes Care, 20; 1183-97 (1997). Diabetic individuals are prone to complications which are a major threat to both the quality and the quantity of life. Almost half those diagnosed with diabetes before the age of 31 years die before they reach 50 years largely as a result of cardiovascular or renal complications, often with many years of crippling and debilitating disease beforehand. See, Deckert T., Poulsen J., Larsen M. Diabetologia 14:363-70 (1978). It is estimated that diabetic individuals have a 25-fold increase in the risk of blindness, a 20-fold increase in the risk of renal failure, a 20-fold increase in the risk of amputation as a result of gangrene, and a 2- to 6-fold increased risk of coronary heart disease and ischemic brain damage. See, Klein R., Klein B., Moss S., Davis M., DeMets D. Diabetes Care 8;311-5 (1985).
Largely because of these long-term complications, the cost of diabetes in the US was estimated as $98 billion in 1997 comprising $44 billion for direct medical costs such as inpatient and outpatient care plus $54 billion for indirect costs such as lost earnings and productivity, and premature death. Medical innovations that can slow the progression of diabetes have tremendous potential to mitigate the associated clinical and cost repercussions See, American Diabetes Association, xe2x80x9cEconomic consequences of diabetes in the US in 1997,xe2x80x9d Diabetes Care 21:296-309(1998).
Elevated blood glucose levels are now regarded as causative of diabetic complications based on results of the Diabetes Complications and Control Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS). See, N Eng J Med. 379:977-85 (1993) and Lancet 352:837-53 (1998). The DCCT and the UKPDS have both demonstrated that the development of complications of diabetes is related with degree of hyperglycemia and that long-term outcome may be ameliorated by rigorous treatment. For example, prognosis is dramatically improved if capillary blood and glycated hemoglobin levels are maintained less than 150 mg/dL and 7.0% respectively.
The mechanism of glucose toxicity in the tissues of patients with diabetes mellitus is unknown. Glucose condenses with free amino groups on structural and functional proteins to form Schiff bases which, in turn, undergo a series of transformations to yield dark-brown Maillard products. It has been proposed that diabetes complications are caused by the non-enzymatic cross-linking of proteins. See, for example, Cerami A., Ulrich P. C., Brownlee M., U.S. Pat. No. 4,758,583 (1988). However, although increased protein cross-linking is seen in the tissues of people long-standing diabetes, the role of Maillard products as a causative factor is certainly not clear. See, for example, Wolff S. P., Jiang Z. Y., Hunt J. V. Free Rad Biol Med 10;339-52 (1991).
Amadori-rearrangement is the most important Maillard transformation because its product, fructosamine, is the precursor of all the browning products. A novel extracellular enzyme which catalyzes the elimination of fructosamines from glycated protein has been isolated. Enzymes which are related have been disclosed. See, for example, Gerhardinger C., et al. J Biol Chem 270(1):218-24 (1995); Saxena, A. K. et al., J Biol Chem 271(51):32803-9 (1996); and Horiuchi T, et al., Agric. Biol. Chem. 53(l):103-110 (1989). Based on its high specificity for glycated protein substrates and its use of oxygen as an acceptor, the enzyme may be classified as fructosamine oxidase 1.5.3. See, Enzyme Nomenclature, Recommendations of the Nomenclature Committee of the International Union of Biochemistry, Academic Press, London pp. 19-22, (1979).
Fructosamine oxidase is a copper metalloenzyme which belongs to the copper amine oxidase group of enzymes which have previously been isolated from bacteria, fungi, yeast, and mammalian sera. Products of the fructosamine oxidase catalyzed reaction are free unglycated protein, a-dicarbonyl sugar, and the active oxygen species superoxide. A highly specific copper chelator, triene, is an irreversible inhibitor of fructosamine oxidase activity. See, for example, Morpurgo L, et al. Biol Met 3:114-7 (1990).
Increased fructosamine oxidase activity may cause many of the recognized sequelae of diabetes by degrading fructosamines bound to basement membrane proteins and generating reactive oxygen species as reaction products. For example, superoxide anions cause an increase in intracellular calcium which modulates the activity of nitric oxide synthase. Nitric oxide is a potent vasodilator and it has been implicated in the vascular dysfunction of early diabetes. See, for example, Ido Y., Kilo C., Williamson J. R. Nephrol Dial Transplant 11 Suppl 5:72-5 (1996). Reactive oxygen species also cause a drastic dose-dependent decrease in de novo synthesis of heparin sulfate proteoglycans leading to a reduction in anionic sites on the glomerular basement membrane and an increase in basement membrane permeability to cationic plasma proteins such as albumin. See, Kashira N., Watanabe Y., Makin H., Wallner E. I., and Kanwar Y. S. Proc Natl Acad Sci USA 89:6309-13 (1992). Increased urinary albumin clearance is a risk indicator in people with diabetes mellitus both for evolving renal disease and for early mortality mainly from coronary heart disease. See, for example, Mattock M. B., Barnes D. J., Viberti G. C., et al. Diabetes 47:1786-92 (1998).
Once natural anti-oxidant defenses are exceeded, hydroxyl radicals may be generated from superoxide via a copper catalyzed Haber-Weiss reaction. See, Halliwell B. and Gutteridge J. M. C. xe2x80x9cFree radicals in Biology and Medicinexe2x80x9d Clarendon Press, Oxford pp. 136-76 (1989). Hydroxyl radicals are extremely reactive species and could cause the permanent site-specific damage to basement membrane proteins and histopathological changes that are typical of diabetic microvascular disease. See, Robbins S. L., Cotran R. S., Kumar V. xe2x80x9cPathologic basis of diseasexe2x80x9d 3rd ed. W. B. Saunders, pp. 991-1061. (1984).
Similarly, any prolonged increase in fructosamine oxidase activity will cause oxidative stress which could account for the excess risk of macrovascular disease and the 75% increase in mortality seen in patients with diabetes mellitus compared with non-diabetic individuals. Recent studies have convincing demonstrated that oxidative modification of low density lipoprotein (LDL) is involved in the development of atherosclerosis of coronary and peripheral arterial vessels and elevated oxidized LDL concentrations are found in subjects with diabetes mellitus. See, Witztum J. L. Br Heart J 69 (Suppl):S12-S18 (1993) and Picard S., Talussot C., Serusclat A. et al. Diabetes and Metabolism 22:25-30 (1996). Oxidative changes to membrane lipids and to membrane protein SH-groups may also cause aberrations in cellular calcium homeostasis and contribute to the increased incidence of cardiac sudden death that is typical of diabetes. See, Yucel D., Aydogdu S., Cehreli S. et al. Clin Chem 44:148-54 (1998).
Triethylenetetramine dihydrochloride, also known as trienes or trien-2HCl or trientine dihydrochloride, is a copper chelating agent. Trienes have been used for treating individuals with Wilson""s disease. See, for example, Dubois R. S., Lancet 2(7676): 775 (1970); Walsh, J. M., Q J Med. 42(167): 441-52 (1973); Haslam, R. H., et al., Dev Pharmacol Ther 1(5): 318-24 (1980). Trienes have also been used to treat individuals with primary biliary cirrhosis. See, for example, Epstein O., et al., Gastroenterology 78(6): 1442-5 (1980). In addition, trienes have been used to inhibit the spontaneous development of hepatitis and hepatic tumors in rats. See, for example, Sone K., et al., Hepatology 23(4): 764-70 (1996). Thus far, trienes have not been used in the treatment of diabetes.
All publications and patent cited herein are hereby incorporated by reference in their entirety.
Excess fructosamine oxidase activity with glycated basement membrane protein substrate plays a vital role in diabetic complications by the formation of xcex1-dicarbonyl and reactive oxygen free radical species.
This damage may be ameliorated by administering specific fructosamine oxidase inhibitors or antagonists selected from the groups: (i) copper chelating agents; (ii) substrate analogues; and (iii) hydrazine compounds.
In one aspect, the present invention consists in a method of treating an individual (human or otherwise) predisposed to and/or suffering from diabetes mellitus with a view to minimizing the consequences of macrovascular and microvascular damage to the patient (e.g., accelerated atherosclerosis, blindness, renal failure, neuropathy, etc.) which comprises, in addition to any treatment in order to control blood glucose levels, at least periodically inhibiting or antagonizing fructosamine oxidase enzyme activity in the patient.
Preferably said inhibition, or antagonism occurs as a result of administration or self-administration of at least one fructosamine oxidase reaction product inhibitor or antagonist.
Preferably any such inhibitor or antagonist is selected from the groups:
(i) copper chelating agents
(ii) substrate analogue
(iii) hydrazine compound
Preferably said inhibitor or antagonist is taken orally.
Preferably said inhibitor or antagonist is taken orally as part of a regime, whether totally oral or not, which also involves the control of blood glucose levels.
In a further aspect, the present invention consists in a pharmaceutical composition (preferably oral) suitable for use in such a method, said composition comprising a fructosamine oxidase inhibitor or antagonist in conjunction with a suitable carrier therefor.
In yet a further aspect, the present invention consists in a pharmaceutical composition for reducing macrovascular and microvascular damage in an individual (including a human) suffering from diabetes mellitus, said composition comprising a fructosamine oxidase inhibitor or antagonist and suitable carrier therefor.
Preferably said carrier can be any diluent, excipient or the like and the dosage form of said pharmaceutical composition can be of any appropriate type whether for oral or other administration or self-administration. Long acting release forms are also envisaged within the present invention.
In still a further aspect, the present invention consists in the use of a fructosamine oxidase inhibitor or antagonist in the manufacture of a pharmaceutical composition comprising the fructosamine oxidase inhibitor or antagonist and a suitable pharmaceutical carrier therefor and which composition is useful in treating an individual (human or otherwise) which or who is suffering from diabetes mellitus to reduce macrovascular and microvascular damage (preferably by a method of the present invention).
In still a further aspect, the present invention consists in combination, the treatment regimes, and/or the medicaments of such regimes previously set forth whether packed together or prescribed together or otherwise.
In still another aspect, the invention consists in a method of treating an individual (human or otherwise) predisposed to and/or suffering from diabetes mellitus, which includes inhibiting or antagonizing fructosamine oxidase enzyme activity in the patient with an agent or agents preferably not contraindicated for the patient. Examples of inhibitor or antagonist include but are not limited to those listed hereinafter.
Preferably in one embodiment said agent(s) is or are copper chelating compound(s) administered or self-administered to the patient.
Examples of suitable copper-chelating compounds include triethylenetetramine dihydrochloride (triene), penicillamine, sar, diamsar, ethylenediamine tetraacetic acid, o-phenanthroline, and histidine.
Preferably in another embodiment, said agent(s) is or are substrate analogue compound(s) administered or self-administered to the patient having an amino acid or peptide moiety with a blocked N-terminal amine group.
Examples of a suitable substrate analogue composition are N-acetylcysteine, captopril, lisinopril and enalapril.
Preferably in another embodiment said agent(s) is or are hydrazine compound(s) administered or self-administered to the patient i.e., a compound having a xe2x80x94NHNH2 moiety.
Examples of a suitable hydrazine compound include diaminoguanidine, hydralazine, and carbidopa.
In still another aspect, the invention consists in a dosage regimen for a method of the present invention and/or using dosage units of the present invention.
In still a further aspect, the present invention consists in the use of a pharmaceutical acceptable compounds being at least one of a substrate analogue, a hydrazine compound and a copper chelator in the manufacture of a dosage unit or pharmaceutical composition useful in treating an individual (human or otherwise) which or who is suffering from diabetes mellitus to reduce macrovascular and microvascular damage.
In another aspect, the invention consists in a dosage unit or pharmaceutical composition for an individual useful in a method of the present invention comprising (preferably in effective fructosamine oxidase reaction product inhibiting or antagonizing amountsxe2x80x94separately or collectively) of a compound (or compounds) being a substrate analogue or a hydrazine compound having an xe2x80x94NHNH2 moiety, or both.
Preferably said dosage unit also includes or said pharmaceutical composition also includes one ore more compounds which are a copper chelators.
Preferably said dosage unit or composition is in an oral dosage form optionally with carriers, excipients or, indeed, even other active agents (e.g., means to lower blood glucose levels).
In still another aspect, the invention consists in a regime or dosage unit or pharmaceutical composition for a diabetic or suspected diabetic individual of the copper chelator, triene, providing for the patient a sufficient fructosamine oxidase inhibiting and/or antagonizing effect to reduce macrovascular and microvascular damage.
In still another aspect, the invention consists in a regime or dosage unit or pharmaceutical composition of captopril for a diabetic or suspected diabetic individual, whether effective or intended to be effective in controlling blood pressure of the diabetic patient (at least in part) or not, providing for the patient a sufficient fructosamine oxidase inhibiting and/or antagonizing effect to reduce macrovascular and microvascular damage.
In yet another aspect, the invention consists in a regime or dosage unit or pharmaceutical composition for a diabetic patient or suspected diabetic patient of a hydrazine compound providing for the patient a sufficient fructosamine oxidase inhibiting and/or antagonizing effect to reduce macrovascular and microvascular damage.
In yet another aspect, the invention consists in a regime or dosage unit or pharmaceutical composition for a diabetic patient or suspected diabetic patient of
(i) acetylcysteine and
(ii) at lease one other fructosamine oxidase inhibitor and/or antagonist, the mix of (i) and (ii) providing for the patient a sufficient fructosamine oxidase inhibiting and/or antagonizing effect to reduce macrovascular and microvascular damage.
In yet another aspect, the invention consists in a regime or dosage unit or pharmaceutical composition for a diabetic patient or suspected diabetic patient of
(i) hydralazine and
(ii) at least one other fructosamine oxidase inhibitor and/or antagonist, the mix of (i) and (ii) providing for the patient a sufficient fructosamine oxidase inhibiting and/or antagonizing effect to reduce macrovascular and microvascular damage.
In still another aspect, the present invention consists in a method of treating an individual (human or otherwise) predisposed to and/or suffering from diabetes mellitus which includes inhibiting and/or antagonizing fructosamine oxidase enzyme activity in the patient with acetylcysteine and hydralazine.
In still another aspect, the invention consists in a regime or dosage unit or pharmaceutical composition for a diabetic or suspected diabetic individual which includes acetylcysteine and hydralazine.
In still a further aspect, the present invention consists in the use of co-administration or serial administration of acetylcysteine and hydralazine for the purpose of reducing macrovascular and microvascular damage in an individual.
Preferably said individual is diabetic.
In yet another aspect, the invention consists in a method of treating and/or reducing the likelihood of diabetic cataract in an individual which comprises at least periodically inhibiting and/or antagonizing fructosamine oxidase enzyme activity in the mammal.
Preferably the method involves the administration or self-administration of effective amounts of triethylenetetramine dihydrochloride (triene).
In another aspect, the invention consists in a method of treating and/or reducing the likelihood of diabetic cardiomyopathy in an individual which comprises at least periodically inhibiting and/or antagonizing fructosamine oxidase enzyme activity in the individual.
Preferably the method involves the administration or self-administration of effective amounts of triethylenetetramine dihydrochloride (triene).
Preferably for any of the aforesaid indications triethylenetetramine dihydrochloride (triene) is administered and/or self administered in concert with another (other) fructosamine oxidase enzyme inhibitor(s) and/or antagonist(s).
Preferably said another inhibitor and/or antagonist or said other inhibitors and/or antagonists is or are administered or self administered to elicit a pharmacological effect for another indication yet together with the effect of the triene is or are in an amount or amounts which are effective for treating or ameliorating macrovascular and microvascular damage of such an individual.
Reference is drawn to PCT Application PCT/NZ99/00161, filed Sep. 24, 1999 (claiming priority of New Zealand Patent Specification No. 332085 filed Sep. 25, 1998), the full content of which is hereby incorporated by reference. It discloses methods of monitoring fructosamine oxidase inhibition and/or antagonism of patients, screening and/or determine patients to determine patients at risk to vascular (particularly microvascular) damage and identifying those individuals who will benefit by treatment with fructosamine oxidase inhibitors and/or antagonists, methods of determining fructosamine oxidase levels in a mammal, methods of determining blood plasma fructosamine oxidase levels in a diabetic individual or a suspected individual, methods of assaying blood serum or blood plasma in vitro for fructosamine oxidase, methods of identifying or testing candidate substances and to related methods and procedures.
Preferably the measurement conducted in vitro is of the superoxide reaction product (or any other oxygen free radical product) of fructosamine oxidase.